Agricultural implements on modern, commercially-viable farms typically are towed or carried by tractors and perform one or more operations on each of a plurality of rows, most commonly eight. The tractor pulls the implement in a direction parallel to the row. For each row, a row unit, typically mounted on a tool bar, performs an operation on the row as the tractor travels forward, such as planting or drilling seed, fertilizing or applying pesticide or herbicide. Conventionally, the rate of planting, fertilization or application of pesticide or herbicide, and the types of agricultural products so deposited, are set in advance of the farmer's entry into the field, and stay in this condition until the current operation is completed on that field.
The farmer, and therefore the agricultural implement manufacturer, is constantly exploring ways to increase yield per acre and efficiency. One approach is to increase agricultural product application accuracy and placement, thus reducing waste even in the context of a constant application rate. Representative of such implements in the subclass of planters and drills are Case Corporation's 955 Series of EARLY RISER CYCLO AIR.RTM. planters, each of which has a central-fill seed hopper for storing seed and a pneumatic seed metering and distribution system to each of a plurality of row units on the tool bar; Case Corporation's EARLY RISER plate planter family; and Case Corporation's 5300, 5400, 5500, 7100 and 7200 drills, which have a variety of row numbers, spacings and seeding widths. These planters and drills apply a single type of seed stored in a seed hopper.
Conventional agricultural practices have treated fields as having characteristics which are constant throughout the field. However, different locations in a field may have dramatic differences in nutrient level, soil depth, insect pressure, weed pressure, drainage, field slope, soil type and other characteristics--and these in turn generate discernable and recordable differences in yield history. More recent practice, therefore, has been to treat a field as having variant characteristics from location to location and to vary the application of an agricultural product as a function of these characteristics. Implements and systems exist which are capable of applying herbicides, insecticides and fertilizers on a site-specific basis; this has become known as prescription farming. Application Ser. No. 08/822,432 filed Mar. 21, 1997, to which this application is related, applies prescription farming techniques to the planting of different seed types in the same field.
Still, further improvements could be made. For example, there is sometimes a difference between the theoretical rate of application, or the rate of application that the designers of the apparatus intend to be applied, and the actual rate of application. While the difference and the rate of change of the difference may be small in many circumstances, the difference and its rate of change may become large because of mechanical malfunction. It therefore would be useful to regulate agricultural product deposition according to actual, real-time implement performance. Further, since at least one agricultural product is applied to a field in an area-variant manner, it would be useful to change the application rates of other agricultural products to take the variation of the first product and the field into account. Finally, present apparatus treat a multiple-row product dispenser as dispensing product to an area having constant characteristics across the width of the toolbar, when in fact substantial variations in critical characteristics may exist from one row to the next. Prescription rates and types could therefore vary among row locations.